Communications

Phase Locked Loop is an important circuit found in various communication devices, and here studied in a set up to synchronize input and local carrier signals for coherent demodulation of AM signals. PLL consists of a phase detector, a loop filter, and a voltage controlled oscillator. The phase detector and loop filter combined produces an error signal which amplitude is linearly related to the phase difference of input and local carrier signals. The voltage-controlled oscillator adjusts appropriately to tune both signals as desired.